Light source device, display unit, and electronic apparatus

ABSTRACT

A display unit includes: a display section displaying an image; and a light source device emitting light for image display toward the display section, the light source device including one or more first light sources, a light guide plate, and an optical member, the first light sources emitting first illumination light, the light guide plate including a plurality of scattering regions that allow the first illumination light to be scattered and then to exit from the light guide plate, the optical member being disposed on a light-emission side of the light guide plate to face the light guide plate and allowing an angular distribution of luminance of the first illumination light emitted from the light guide plate to be varied.

BACKGROUND

The present disclosure relates to a light source device and a displayunit capable of achieving stereoscopic vision by a parallax barriersystem, and an electronic apparatus.

As one of stereoscopic display systems capable of achieving stereoscopicvision with naked eyes without wearing special glasses, a parallaxbarrier system stereoscopic display unit is known. In the stereoscopicdisplay unit, a parallax barrier is disposed to face a front side (adisplay plane side) of a two-dimensional display panel. In a typicalconfiguration of the parallax barrier, shielding sections shieldingdisplay image light from the two-dimensional display panel andstripe-shaped opening sections (slit sections) allowing the displayimage light to pass therethrough are alternately arranged in ahorizontal direction.

In the parallax barrier system, parallax images for stereoscopic vision(a right-eye parallax image and a left-eye parallax image in the case oftwo perspectives) which are spatially separated from one another aredisplayed on the two-dimensional display panel, and the parallax imagesare separated in the horizontal direction by the parallax barrier toachieve stereoscopic vision. When a slit width or the like in theparallax barrier is appropriately determined, in the case where a viewerwatches the stereoscopic display unit from a predetermined position anda predetermined direction, light rays from different parallax imagesenter respective right and left eyes of the viewer through the slitsections.

It is to be noted that, in the case where, for example, a transmissiveliquid crystal display panel is used as the two-dimensional displaypanel, a parallax barrier may be disposed behind the two-dimensionaldisplay panel (refer to FIG. 10 in Japanese Patent No. 3565391 and FIG.3 in Japanese Unexamined Patent Application Publication No.2007-187823). In this case, the parallax barrier is disposed between thetransmissive liquid crystal display panel and a backlight.

SUMMARY

In parallax barrier system stereoscopic display units, a componentexclusive for three-dimensional display, i.e., a parallax barrier isnecessary; therefore, more components and a larger space for thecomponents are necessary, compared to a typical display unit fortwo-dimensional display.

It is desirable to provide a light source device and a display unitcapable of achieving a function equivalent to a parallax barrier withuse of a light guide plate and obtaining illumination light with adesired angular distribution of luminance, and an electronic apparatus.

According to an embodiment of the present disclosure, there is provideda light source device including: one or more first light sourcesemitting first illumination light; a light guide plate including aplurality of scattering regions that allow the first illumination lightto be scattered and then to exit from the light guide plate; and anoptical member disposed on a light-emission side of the light guideplate to face the light guide plate and allowing an angular distributionof luminance of the first illumination light emitted from the lightguide plate to be varied.

According to an embodiment of the present disclosure, there is provideda display unit including: a display section displaying an image; and alight source device emitting light for image display toward the displaysection, the light source device including one or more first lightsources, a light guide plate, and an optical member, the first lightsources emitting first illumination light, the light guide plateincluding a plurality of scattering regions that allow the firstillumination light to be scattered and then to exit from the light guideplate, the optical member being disposed on a light-emission side of thelight guide plate to face the light guide plate and allowing an angulardistribution of luminance of the first illumination light emitted fromthe light guide plate to be varied.

According to an embodiment of the present disclosure, there is providedan electronic apparatus provided with a display unit, the display unitincluding: a display section displaying an image; and a light sourcedevice emitting light for image display toward the display section, thelight source device including one or more first light sources, a lightguide plate, and an optical member, the first light sources emittingfirst illumination light, the light guide plate including a plurality ofscattering regions that allow the first illumination light to bescattered and then to exit from the light guide plate, the opticalmember being disposed on a light-emission side of the light guide plateto face the light guide plate and allowing an angular distribution ofluminance of the first illumination light emitted from the light guideplate to be varied.

In the light source device, the display unit, and the electronicapparatus according to the embodiments of the present disclosure, thefirst illumination light from the first light source is scattered by thescattering regions to exit from the light guide plate. Therefore, thelight guide plate has a function as a parallax barrier for the firstillumination light. In other words, the light guide plate equivalentlyfunctions as a parallax barrier with the scattering regions as openingsections (slit sections). Therefore, three-dimensional display ispossible. Moreover, the angular distribution of luminance of the firstillumination light emitted from the light guide plate is varied by theoptical member.

In the light source device, the display unit, and the electronicapparatus according to the embodiments of the present disclosure, thelight guide plate has the plurality of scattering regions allowing thefirst illumination light to be scattered; therefore, the light guideplate equivalently has a function as a parallax barrier for the firstillumination light. Moreover, the optical member allowing the angulardistribution of luminance of the first illumination light emitted fromthe light guide plate to be varied is provided; therefore, illuminationlight with a desired angular distribution of luminance is obtainable.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary, and are intended toprovide further explanation of the technology as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the technology, and are incorporated in and constitutea part of this specification. The drawings illustrate embodiments and,together with the specification, serve to explain the principles of thetechnology.

FIG. 1 is a sectional view illustrating a configuration example of adisplay unit according to a first embodiment of the present disclosure.

FIG. 2 is a plan view illustrating an example of a pixel configurationof a display section.

FIG. 3 is a sectional view illustrating an example of a state ofemission of light rays when only a first light source is maintained inan ON (turned-on) state.

FIG. 4 is a plan view illustrating an example of an in-plane lightemission pattern when only the first light source is maintained in theON (turned-on) state.

FIG. 5 is a sectional view illustrating an example of a state ofemission of light rays when only a second light source is maintained inthe ON (turned-on) state.

FIG. 6 is a plan view illustrating an example of an in-plane lightemission pattern when only the second light source is maintained in theON (turned-on) state.

FIG. 7 is an explanatory diagram illustrating a first configurationexample of scattering regions when the first light sources are disposedon a top side and a bottom side.

FIG. 8 is an explanatory diagram illustrating a second configurationexample of the scattering regions when the first light sources aredisposed on the top side and the bottom side.

FIG. 9 is an explanatory diagram illustrating a configuration example ofthe scattering regions when only one first light source is provided.

FIG. 10 is an explanatory diagram illustrating a configuration exampleof the scattering regions when the first light sources are disposed on aright side and a left side.

FIG. 11 is a sectional view illustrating an example of an angulardistribution of luminance of light emitted from the first light sourceand an angular distribution of luminance of light emitted from thesecond light source.

FIG. 12 is an explanatory diagram illustrating an example of the angulardistribution of luminance of the light emitted from the first lightsource or the angular distribution of luminance of the light emittedfrom the second light source.

FIG. 13 is a sectional view illustrating a configuration example of areverse prism.

FIG. 14 is a sectional view illustrating an example of variation inangular distribution of luminance of light by a reverse prism sheet.

FIG. 15 is an explanatory diagram illustrating an example of variationin angular distribution of luminance of light by the reverse prismsheet.

FIG. 16 is a plan view and a sectional view illustrating an example ofthe angular distribution of luminance of the light emitted from thefirst light source.

FIG. 17 is a plot illustrating an example of an angular distribution ofluminance of light emitted from the first light source in a firstregion.

FIG. 18 is a plot illustrating an example of an angular distribution ofluminance of light emitted from the first light source in a secondregion.

FIG. 19 is a plot illustrating an example of an angular distribution ofluminance of light emitted from the first light source in a thirdregion.

FIG. 20 is a sectional view illustrating an example of variation inangular distribution of luminance of light by the reverse prism sheetwhen only one first light source is provided.

FIG. 21 is an explanatory diagram illustrating an example of variationin angular distribution of luminance of light by the reverse prism sheetwhen only one first light source is provided.

FIG. 22 is a plan view illustrating a relationship between a pattern ofthe scattering region and a ridgeline of a reverse prim when the firstlight sources are disposed on the top side and the bottom side.

FIG. 23 is a plan view illustrating a relationship between a pattern ofthe scattering region and the ridgeline of the reverse prism when thefirst light sources are disposed on the right side and the left side.

FIG. 24 is an explanatory diagram of an observation direction of anin-plane light emission pattern.

FIG. 25 is an enlarged plan view illustrating a light emission statewhen a light guide plate is viewed from a front direction in the casewhere the pattern of the scattering region and the ridgeline of thereverse prism are orthogonal to each other.

FIG. 26 is an enlarged plan view illustrating a first example of a lightemission state when the light guide plate is viewed from the frontdirection in the case where the pattern of the scattering region and theridgeline of the reverse prism are not orthogonal to each other.

FIG. 27 is an enlarged plan view illustrating a second example of thelight emission state when the light guide plate is viewed from the frontdirection in the case where the pattern of the scattering region and theridgeline of the reverse prism are not orthogonal to each other.

FIG. 28 is a sectional view illustrating an effect obtained througharranging the pattern of the scattering region and the ridgeline of thereverse prism orthogonal to each other.

FIG. 29 is a plot illustrating an example of an angular distribution ofluminance in a horizontal direction of light emitted from the firstlight source.

FIG. 30 is a plot illustrating an example of an angular distribution ofluminance in a vertical direction of light emitted from the first lightsource.

FIG. 31 is a plot illustrating an example of an angular distribution ofluminance in the horizontal direction of light emitted from the secondlight source.

FIG. 32 is a plot illustrating an example of an angular distribution ofluminance in the vertical direction of light emitted from the secondlight source.

FIG. 33 is a sectional view illustrating a configuration example of adisplay unit according to a second embodiment.

FIG. 34 is a sectional view illustrating a configuration example of anupward prism.

FIG. 35 is a sectional view illustrating a configuration example of adisplay unit according to a third embodiment.

FIG. 36 is a sectional view illustrating a configuration example of adisplay unit according to a fourth embodiment.

FIG. 37 is a sectional view illustrating a first configuration exampleof a display unit according to a fifth embodiment.

FIG. 38 is a sectional view illustrating a second configuration exampleof the display unit according to the fifth embodiment.

FIG. 39 is a plan view illustrating a modification of the pattern of thescattering region.

FIG. 40 is an appearance diagram illustrating an example of anelectronic apparatus.

DETAILED DESCRIPTION

Some embodiments of the present disclosure will be described in detailbelow referring to the accompanying drawings. It is to be noted thatdescription will be given in the following order.

1. First Embodiment

A configuration example in which a reverse prism sheet is provided as anoptical member allowing an angular distribution of luminance of light tobe varied

2. Second Embodiment

A configuration example in which an upward prism sheet is provided as anoptical member allowing an angular distribution of luminance of light tobe varied

3. Third Embodiment

A modification of a position of the reverse prism sheet

4. Fourth Embodiment

A configuration example in which a reflection member is provided

5. Fifth Embodiment

A modification of a second light source

6. Other Embodiments

A configuration example of an electronic apparatus, and the like

1. First Embodiment Entire Configuration of Display Unit

FIG. 1 illustrates a configuration example of a display unit accordingto a first embodiment of the present disclosure. The display unitincludes a display section 1 which displays an image and a light sourcedevice which is disposed on a back side of the display section 1 andemits light for image display toward the display section 1. The lightsource device includes a first light source 2 (a 2D/3D-display lightsource), a light guide plate 3, and a second light source 7 (a2D-display light source). The light guide plate 3 has a first internalreflection plane 3A facing the display section 1 and a second internalreflection plane 3B facing the second light source 7. The display unitfurther includes a reverse prism sheet 50 disposed between the displaysection 1 and the light guide plate 3. It is to be noted that thedisplay unit includes a control circuit for the display section 1 or thelike which is necessary for display; however, the control circuit or thelike has a configuration similar to that of a typical control circuitfor display or the like, and will not be described here. Moreover, thelight source device includes a control circuit (not illustrated) whichcontrols ON (turned-on) and OFF (turned-off) states of the first lightsource 2 and the second light source 7.

It is to be noted that, in the embodiment, a first direction (a verticaldirection) in a display plane (a plane where pixels are arranged) of thedisplay section 1 or a plane parallel to the second internal reflectionplane 3B of the light guide plate 3 is referred to as a Y direction, anda second direction (a horizontal direction) orthogonal to the firstdirection is referred to as an X direction.

The display unit is capable of arbitrarily and selectively performingswitching between a two-dimensional (2D) display mode on an entirescreen and a three-dimensional (3D) display mode on the entire screen.Switching between the two-dimensional display mode and thethree-dimensional display mode is performed by switching control ofimage data which is to be displayed on the display section 1 and ON/OFFswitching control of the first light source 2 and the second lightsource 7. FIG. 3 schematically illustrates a state of emission of lightrays from the light source device when only the first light source 2 ismaintained in an ON (turned-on) state, and corresponds to thethree-dimensional display mode. FIG. 4 illustrates an example of anin-plane light emission pattern of light emitted from the light guideplate 3 when only the first light source 2 is maintained in an ON(turned-on) state. FIG. 5 schematically illustrates a state of emissionof light rays from the light source device when only the second lightsource 7 is maintained in an ON (turned-on) state, and corresponds tothe two-dimensional display mode. FIG. 6 illustrates an example of anin-plane light emission pattern of light emitted from the light guideplate 3 when only the second light source 7 is maintained in the ON(turned-on) state. It is to be noted that, as illustrated in FIGS. 7 to10, and the like which will be described later, the first light source 2may be disposed at any of various positions. FIGS. 4 and 6 illustrate aconfiguration example when the first light sources 2 are disposed on afirst side surface and a second side surface in the vertical direction(the Y direction) in the light guide plate 3 to face each other. FIGS.1, 3, and 5 illustrate the first light sources 2 as if to be disposed ona third side surface and a fourth side surface in the horizontaldirection (the X direction) in the light guide plate 3 to face eachother; however, the positions of the first light sources 2 are shownonly virtually to describe an emission state of light rays.

The display section 1 is configured with use of a transmissivetwo-dimensional display panel, for example, a transmissive liquidcrystal display panel. For example, as illustrated in FIG. 2, thedisplay section 1 includes a plurality of pixels 11 configured of, forexample, R (red) pixels 11R, G (green) pixels 11G, and B (blue) pixels11B, and the plurality of pixels 11 are arranged in a matrix form. Thedisplay section 1 displays a two-dimensional image through modulatinglight of each color from the light source device from one pixel 11 toanother based on image data. The display section 1 arbitrarily andselectively switches images to be displayed between a plurality ofperspective images based on three-dimensional image data and an imagebased on two-dimensional image data. It is to be noted that thethree-dimensional image data is, for example, data including a pluralityof perspective images corresponding to a plurality of view angledirections in three-dimensional display. For example, in the case wherebinocular three-dimensional display is performed, the three-dimensionalimage data is data including perspective images for right-eye displayand left-eye display. In the case where display is performed in thethree-dimensional display mode, for example, a composite image includinga plurality of stripe-shaped perspective images in one screen isproduced and displayed.

The first light source 2 is configured with use of, for example, afluorescent lamp such as a CCFL (Cold Cathode Fluorescent Lamp), or anLED (Light Emitting Diode). The first light source 2 emits firstillumination light L1 (refer to FIG. 3) from a side surface of the lightguide plate 3 into an interior thereof. One or more first light sources2 are disposed on one or more side surfaces of the light guide plate 3.For example, in the case where the light guide plate 3 has a rectangularplanar shape, the light guide plate 3 has four side surfaces, and it isonly necessary to dispose one or more first light sources 2 on one ormore of the four side surfaces. FIG. 1 illustrates a configurationexample in which the first light source 2 is disposed on each of twoside surfaces facing each other of the light guide plate 3. The firstlight source 2 is ON (turned-on)/OFF (not turned-on) controlled inresponse to switching between the two-dimensional display mode and thethree-dimensional display mode. More specifically, in the case where thedisplay section 1 displays an image based on the three-dimensional imagedata (in the case of the three-dimensional display mode), the firstlight source 2 is controlled to be turned on, and in the case where thedisplay section 1 displays an image based on the two-dimensional imagedata (in the case of the two-dimensional display mode), the first lightsource 2 is controlled to be either turned off or turned on.

The second light source 7 is disposed to face the second internalreflection plane 3B of the light guide plate 3. The second light source7 emits second illumination light L10 toward the light guide plate 3from a direction different from the direction where the first lightsource 2 emits the first illumination light L1. More specifically, thesecond light source 7 emits the second illumination light L10 from anexternal side (the back side of the light guide plate 3) toward thesecond internal reflection plane 3B (refer to FIG. 5). The second lightsource 7 may be a planar light source. For example, a configurationcontaining a light-emitting body such as a CCFL or an LED and using alight-scattering plate scattering light emitted from the light-emittingbody, or the like is considered. The second light source 7 is ON(turned-on)/OFF (turned-off) controlled in response to switching betweenthe two-dimensional display mode and the three-dimensional display mode.More specifically, in the case where the display section 1 displays animage based on the three-dimensional image data (in the case of thethree-dimensional display mode), the second light source 7 is controlledto be turned off, and in the case where the display section 1 displaysan image based on the two-dimensional image data (in the case of thetwo-dimensional display mode), the second light source 7 is controlledto be turned on.

The light guide plate 3 is configured of a transparent plastic plate of,for example, an acrylic resin. All surfaces except for the secondinternal reflection plane 3B of the light guide plate 3 are entirelytransparent. For example, in the case where the light guide plate 3 hasa rectangular planar shape, the first internal reflection plane 3A andfour side surfaces are entirely transparent.

The entire first internal reflection plane 3A is mirror-finished, andallows light rays incident at an incident angle satisfying atotal-reflection condition to be reflected, in a manner oftotal-internal-reflection, in the interior of the light guide plate 3and allows light rays out of the total-reflection condition to exittherefrom.

The second internal reflection plane 3B has scattering regions 31 and atotal-reflection region 32. As will be described later, light-scatteringcharacteristics are added to the scattering regions 31 throughperforming laser processing, sandblast processing, or the like on asurface of the light guide plate 3. On the second internal reflectionplane 3B, in the three-dimensional display mode, the scattering regions31 and the total-reflection region 32 function as opening sections (slitsections) and a shielding section, respectively, of a parallax barrierfor the first illumination light L1 from the first light source 2. Onthe second internal reflection plane 3B, the scattering regions 31 andthe total-reflection region 32 are arranged in a pattern forming aconfiguration corresponding to a parallax barrier. In other words, thetotal-reflection region 32 is arranged in a pattern corresponding to ashielding section in the parallax barrier, and the scattering regions 31each are arranged in a pattern corresponding to an opening section inthe parallax barrier. It is to be noted that, as a barrier pattern ofthe parallax barrier, for example, any of various patterns such as astripe-shaped pattern in which a large number of vertically longslit-like opening sections are arranged side by side in the horizontaldirection with shielding sections in between may be used, and thebarrier pattern of the parallax barrier is not specifically limited.FIG. 4 illustrates an example of an in-plane light emission pattern oflight emitted from the light guide plate 3 (light L20 (refer to FIG. 3)emitted from the first light source 2) in the case where a plurality ofscattering regions 31 extending in the vertical direction are arrangedside by side in a striped form.

The first internal reflection plane 3A and the total-reflection region32 of the second internal reflection plane 3B reflect light raysincident at an incident angle θ1 satisfying a total-reflection conditionin a manner of total-internal-reflection (reflect light rays incident atthe incident angle θ1 larger than a predetermined critical angle α in amanner of total-internal-reflection). Therefore, the first illuminationlight L1 incident from the first light source 2 at the incident angle θ1satisfying the total-reflection condition is guided to a side surfacedirection by internal total reflection between the first internalreflection plane 3A and the total-reflection region 32 of the secondinternal reflection plane 3B. Moreover, as illustrated in FIG. 5, thetotal-reflection region 32 allows the second illumination light L10 fromthe second light source 7 to pass therethrough and to travel, as a lightray out of the total-reflection condition, toward the first internalreflection plane 3A.

It is to be noted that the critical angle α is represented as follows,where the refractive index of the light guide plate 3 is n1, and therefractive index of a medium (an air layer) outside the light guideplate 3 is n0 (<n1). The angles α and θ1 are angles with respect to anormal to a surface of the light guide plate. The incident angle θ1satisfying the total-reflection condition is θ1>α.

sin α=n0/n1

As illustrated in FIG. 3, the scattering regions 31 scatter and reflectthe first illumination light L1 from the first light source 2 and allowa part or a whole of the first illumination light L1 to travel, as alight ray, i.e., an emission light ray L20, out of the total-reflectioncondition, toward the first internal reflection plane 3A.

The reverse prism sheet 50 is disposed to face a predetermined sidewhere the first illumination light L1 exits (a side where the displaysection 1 is disposed) of the light guide plate 3. The reverse prismsheet 50 includes a plurality of reverse prisms 51. The reverse prismsheet 50 optimizes light emitted from the light guide plate 3 throughvarying an angular distribution of luminance of the first illuminationlight L1 (the emission light ray L20) emitted from the light guide plate3 and an angular distribution of luminance of the second illuminationlight L10 so as to allow the light emitted from the light guide plate 3to have a desired angular distribution of luminance. Optimization of theangular distribution of luminance of light by the reverse prism sheet 50will be described in detail later.

[Basic Operation of Display Unit]

In the case where the display unit performs display in thethree-dimensional display mode, the display section 1 displays an imagebased on the three-dimensional image data, and ON (turned-on)/OFF(turned-off) control of the first light source 2 and the second lightsource 7 is performed for three-dimensional display. More specifically,as illustrated in FIG. 3, the first light source 2 is controlled to bein the ON (turned-on) state, and the second light source 7 is controlledto be in the OFF (turned-off) state. In this state, the firstillumination light L1 from the first light source 2 is reflectedrepeatedly in a manner of total-internal-reflection between the firstinternal reflection plane 3A and the total-reflection region 32 of thesecond internal reflection plane 3B in the light guide plate 3 to beguided from a side surface where the first light source 2 is disposed tothe other side surface facing the side surface and then to be emittedfrom the other side surface. On the other hand, a part of the firstillumination light L1 from the first light source 2 is scattered andreflected by the scattering regions 31 of the light guide plate 3 topass through the first internal reflection plane 3A of the light guideplate 3 and exit from the light guide plate 3. The in-plane lightemission pattern of the light emitted from the light guide plate 3 inthis case (the emitted light L20 from the first light source 2 (refer toFIG. 3)) is, for example, as illustrated in FIG. 4. Thus, the lightguide plate 3 is allowed to have a function as a parallax barrier. Inother words, for the first illumination light L1 from the first lightsource 2, the light guide plate 3 equivalently functions as a parallaxbarrier with the scattering regions 31 as opening sections (slitsections) and the total-reflection region 32 as a shielding section.Therefore, three-dimensional display by a parallax barrier system inwhich the parallax barrier is disposed on the back side of the displaysection 1 is equivalently performed.

On the other hand, in the case where display is performed in thetwo-dimensional display mode, the display section 1 displays an imagebased on the two-dimensional image data, and ON (turned-on)/OFF(turned-off) control of the first light source 2 and the second lightsource 7 is performed for two-dimensional display. More specifically,for example, as illustrated in FIG. 5, the first light source 2 iscontrolled to be in the OFF (turned-off) state, and the second lightsource 7 is controlled to be in the ON (turned-on) state. In this case,the second illumination light L10 from the second light source 7 passesthrough the total-reflection region 32 of the second internal reflectionplane 3B to exit as a light ray out of the total-reflection conditionfrom substantially the entire first internal reflection plane 3A of thelight guide plate 3. The in-plane light emission pattern of lightemitted from the light guide plate 3 in this case (light emitted fromthe second light source 7) is, for example, as illustrated in FIG. 6. Inother words, the light guide plate 3 functions as a planar light sourcesimilar to a typical backlight. Therefore, two-dimensional display by abacklight system in which a typical backlight is disposed on the backside of the display section 1 is equivalently performed.

It is to be noted that, when only the second light source 7 is turnedon, the second illumination light L10 exits from substantially theentire surface of the light guide plate 3; however, if necessary, thefirst light source 2 may be turned on. For example, in the case wherethere is a difference in a luminance distribution between portionscorresponding to the scattering regions 31 and a portion correspondingto the total-reflection region 32 when only the second light source 7 isturned on, the lighting state of the first light source 2 isappropriately adjusted (ON/OFF control or the lighting amount of thefirst light source 2 is adjusted) to allow an entire luminancedistribution to be optimized. However, for example, in the case whereluminance is sufficiently corrected in the display section 1 whentwo-dimensional display is performed, it is only necessary to turn onthe second light source 7.

[Specific Configuration Examples of Scattering Region 31]

Specific configuration examples of the scattering region 31 will bedescribed referring to FIGS. 7 to 10. FIGS. 7 to 10 illustrateconfiguration examples in the case where a plurality of scatteringregions 31 continuously extending in the vertical direction are arrangedside by side in a striped form. The light-scattering characteristics areadded to the scattering regions 31 through forming a plurality ofasperities 41 in the scattering regions 31. Moreover, the scatteringregions 31 have a configuration in which density of the asperities 41varies with a distance from the first light source 2. In the case wherea width of each of the scattering regions 31 is uniform in the extendingdirection, when the density of the asperities 41 is uniform irrespectiveof the distance from the first light source 2, the amount of lightemitted from the light guide plate 3 increases with decreasing distancefrom the first light source 2, and luminance of the emitted lightincreases with decreasing distance from the first light source 2.Therefore, in-plane luminance becomes nonuniform. When the density ofthe asperities 41 varies with the distance from the first light source2, non-uniformity of the in-plane luminance is allowed to be reduced.

FIG. 7 illustrates a first configuration example of the scatteringregion 31 when the first light sources 2 are disposed on a first sidesurface and a second side surface in the vertical direction (the Ydirection) in the light guide plate 3 to face each other. In thisconfiguration example, the light-scattering characteristics are added tothe scattering regions 31 through forming a plurality of very smallasperities 41 on a surface corresponding to each of the scatteringregions 31 of the light guide plate 3 by, for example, laser processingor sandblast processing. Moreover, as illustrated in FIG. 7, the densityof the asperities 41 varies with the distance from each of the firstlight sources 2 (distances from the first side surface and the secondside surface of the light guide plate 3). More specifically, the densityof the asperities 41 increases with increasing distance from each of thefirst light sources 2. Since the first light sources 2 are disposed ontwo side surfaces in the Y direction, each of the scattering regions 31is configured to have the highest density of the asperities 41 in acentral portion in the Y direction. When light enters each of thescattering regions 31, probability that light is applied to theasperities 41 is increased through increasing the density of theasperities 41 with increasing distance from each of the first lightsources 2. When the probability that light is applied to the asperitiesis increased, probability that light is scattered and reflected to exitfrom the light guide plate 3 is also increased. In other words,luminance is improved.

FIG. 8 illustrates a second configuration example of the scatteringregion 31 when the first light sources 2 are disposed on the first sidesurface and the second side surface in the vertical direction (the Ydirection) in the light guide plate 3 to face each other. In thisconfiguration example, as illustrated in FIG. 8, one scattering region31 is formed in a steric convex pattern as a whole. The light-scatteringcharacteristics are added to the scattering regions 31 through forming aplurality of very small asperities 41 on a surface (an interface) of thesteric pattern by, for example, laser processing or sandblastprocessing. As with the configuration example in FIG. 7, the density ofthe asperities 41 varies with the distance from each of the first lightsources 2 (the distances from the first side surface and the second sidesurface of the light guide plate 3).

FIG. 9 illustrates a configuration example of the scattering region 31when the first light source 2 is disposed only on the first side surfacein the vertical direction (the Y direction) in the light guide plate 3.In this configuration example, only one first light source 2 isdisposed, unlike the configuration example illustrated in FIG. 7. Sincethe first light source 2 is disposed only on the first side surface (anupper side surface) in the Y direction, the density of the asperities 41decreases with decreasing distance to the first side surface, andincreases with decreasing distance to the second side surface (a lowerside surface) in the Y direction. It is to be noted that, also in thisconfiguration example, as with the configuration example in FIG. 8, onescattering region 31 may be configured in a steric convex pattern as awhole.

FIG. 10 illustrates a configuration example of the scattering region 31when the first light sources 2 are disposed on a third side surface anda fourth side surface in a horizontal direction (the X direction) in thelight guide plate 3 to face each other. Since, in this configurationexample, unlike the configuration example in FIG. 7, the first lightsources 2 are disposed in the X direction, the scattering region 31 isconfigured to have the highest density of the asperities 41 in a centralportion in the X direction. Moreover, the density of the asperities 41decreases with decreasing distance to each of the third side surface andthe fourth side surface in the X direction. It is to be noted that, alsoin this configuration example, as with the configuration example in FIG.8, one scattering region 31 may be configured in a steric convex patternas a whole.

It is to be noted that, when the luminance distribution of light emittedfrom the first light source 2 is improved by any of the configurationsillustrated in FIGS. 7 to 10, the angular distribution of luminance oflight emitted from the second light source 7 preferably approximate tothe angular distribution of luminance of light emitted from the firstlight source 2. For example, as with the above-described configurationsof the scattering region 31, a plurality of very small asperities arepreferably formed on a front surface of the second light source 7 by,for example, sandblast processing.

[Optimization of Angular Distribution of Luminance of Light by ReversePrism Sheet 50]

Non-uniformity of the in-plane luminance distribution by the distancefrom the first light source 2 is allowed to be reduced by any of theabove-described configurations in FIGS. 7 to 10. On the other hand, theangular distribution of luminance of light emitted from the light guideplate 3 may vary from a desired state depending on roughness of theasperities 41 in the scattering region 31. For example, as illustratedin FIGS. 11 and 12, light emitted from the first light source 2 does nottravel toward a front direction to cause a reduction in front luminance.In other words, light emitted from the first light source 2 has anangular distribution of luminance, where luminance in an obliquedirection is higher than luminance in a direction of a normal to asurface of the light guide plate 3. FIG. 12 illustrates an angulardistribution of luminance at an angle Yθ in the Y direction of lightemitted from the first light source 2, as illustrated in FIG. 11.Moreover, FIG. 12 illustrates an angular distribution of luminance oflight when the first light sources 2 are disposed on the first sidesurface and the second side surface in the vertical direction (the Ydirection) in the light guide plate 3 to face each other. It is to benoted that, when the second light source 7 has a configuration in whichthe angular distribution of luminance of light emitted from the secondlight source 7 approximate to the angular distribution of luminance oflight emitted from the first light source 2 in the above-describedmanner, the angular distribution of luminance may vary in a similarmanner.

For example, as illustrated in FIGS. 16 to 19, the angular distributionof luminance may vary differently depending on an in-plane position.FIG. 17 illustrates an example of an angular distribution of luminanceof light emitted from the first light source 2 on an upper portion (afirst region 71A) in the Y direction as illustrated in FIG. 16. FIG. 18illustrates an example of an angular distribution of luminance of lightemitted from the first light source 2 in a central portion (a secondregion 71B) as illustrated in FIG. 16. FIG. 19 illustrates an example ofan angular distribution of luminance of light emitted from the firstlight source 2 on a lower portion (a third region 71C) in the Ydirection as illustrated in FIG. 16. In FIGS. 17 to 19, an angulardistribution of luminance at the angle Yθ in the Y direction isillustrated as with FIG. 12. Moreover, FIGS. 17 to 19 illustrate theangular distribution of luminance when the first light sources 2 aredisposed on the first side surface and the second side surface in thevertical direction (the Y direction) in the light guide plate 3 to faceeach other.

As illustrated in FIGS. 13 to 15, the reverse prism sheet 50 reduces theabove-described variations in the angular distribution of luminancethrough shifting light emitted from the light guide plate 3 toward thefront direction (the direction of the normal to the surface of the lightguide plate 3). Each of the reverse prisms 51 of the reverse prism sheet50 includes a first oblique plane 53, a second oblique plane 54, and aridgeline 52 which is formed at an intersection of the first obliqueplane 53 and the second oblique plane 54, as illustrated in FIG. 13. Asillustrated in FIGS. 13 and 14, a traveling direction of light emittedfrom the light guide plate 3 is changed at the first oblique plane 53and the second oblique plane 54 of the reverse prism 51 throughrefraction and total reflection.

As described above, in each of the first light source 2 and the secondlight source 7, light emitted from the light guide plate 3 has anangular distribution of luminance, where luminance in the obliquedirection is higher than luminance in the direction of the normal to thesurface of the light guide plate 3. The reverse prism sheet 50 allows anangular distribution of luminance of light emitted from the light guideplate 3 to be so varied as to increase luminance at least in thedirection of the normal, thereby improving the angular distributions ofluminance of light in each of the first light source 2 and the secondlight source 7. More preferably, the reverse prism sheet 50 allows theangular distribution of luminance of light emitted from the light guideplate 3 to be so varied as to decrease luminance in the obliquedirection. Thus, the emitted light after passing through the reverseprism sheet 50 has an angular distribution of luminance, where luminancein the front direction is highest, as illustrated by a dotted line inFIG. 15.

It is to be noted that, although an effect by the reverse prism sheet 50when the first light sources 2 are disposed on the first side surfaceand the second side surface in the vertical direction (the Y direction)in the light guide plate 3 to face each other is described above, asimilar effect is obtained when the first light sources 2 are disposedon the third side surface and the fourth side surface in the horizontaldirection (the X direction) to face each other (refer to FIG. 10).

Moreover, for example, as illustrated in FIGS. 20 and 21, an angulardistribution of luminance of light when only one first light source isprovided is also improvable. FIGS. 20 and 21 illustrate an example whenthe first light source 2 is disposed only on the first side surface inthe vertical direction (the Y direction) in the light guide plate 3. Inthis case, light emitted from the light guide plate 3 has an angulardistribution of luminance, where luminance in an oblique direction ishigh on a side opposite to a side where the first light source 2 isdisposed, as indicated by a solid line in FIG. 21. Also in this case,the reverse prism sheet 50 allows the angular distribution of luminanceof light emitted from the light guide plate 3 to be so varied as toincrease luminance at least in the direction of the normal, therebyimproving the angular distribution of luminance. More preferably, thereverse prism sheet 50 allows the angular distribution of luminance ofthe light emitted from the light guide plate 3 to be so varied as todecrease luminance in the oblique direction. Thus, the emitted lightpassing through the reverse prism sheet 50 has an angular distributionof luminance, where luminance in the front direction is highest, asindicated by a dotted line in FIG. 21.

Optimization of the angular distribution of luminance of light isachievable by the reverse prism sheet 50 in the above-described manner,and in this case, the ridgeline 52 of each prism in the reverse prismsheet 50 and an extending direction of each of the scattering regions 31are preferably orthogonal to each other not only in the case where thefirst light sources 2 are disposed on the first side surface and thesecond side surface in the vertical direction (the Y direction) in thelight guide plate 3 to face each other, as illustrated in FIG. 22, butalso in the case where the first light sources 2 are disposed on thethird side surface and the fourth side surface in the horizontaldirection (the X direction) to face each other, as illustrated in FIG.23.

When the ridgeline 52 of each prism in the reverse prism sheet 50 andthe extending direction of each of the scattering regions 31 are notorthogonal to each other, in the case where 3D display is performed bythe first light sources 2, an unnecessary region emits light to cause anincrease in crosstalk. Moreover, to suppress crosstalk, it is preferablethat the reverse prism sheet 50 not include a volume scattering objectsuch as haze in a material thereof, and a prism plane and a planelocated closer to the display section 1 be nearly mirror planes.

FIG. 25 illustrates an enlarged view of a light emission state by thefirst light source 2 when the light guide plate 3 is viewed from thefront direction in the case where the ridgeline 52 of each prism in thereverse prism sheet 50 and the extending direction of each of thescattering regions 31 are orthogonal to each other. In FIG. 25, onlyportions corresponding to the scattering regions 31 emit light. On theother hand, FIGS. 26 and 27 illustrate enlarged views of a lightemission state by the first light source 2 when the ridgeline 52 of eachprism in the reverse prism sheet 50 and the extending direction of eachof the scattering regions 31 are not orthogonal to each other. In FIGS.26 and 27, unnecessary regions other than the portions corresponding tothe scattering regions 31 emit light. In such a state, crosstalk occurswhen 3D display is performed. It is to be noted that FIGS. 25 to 27 eachillustrate a state observed from a direction of a normal to a surface ofthe reverse prism sheet 50, as illustrated in FIG. 24.

A reason why the light emission state differs by a relationship betweenthe ridgeline 52 of each prism in the reverse prism sheet 50 and theextending direction of each of the scattering regions 31, as illustratedin FIGS. 25 to 27, will be described below referring to FIG. 28. FIG. 28illustrates behavior of light rays at a section A-A′ (refer to FIG. 22)in a direction parallel to the pattern of the scattering region 31 inthe light guide plate 3. FIG. 28 illustrates an example when an upperlight source 2-2 and a lower light source 2-1 are disposed in thevertical direction (the Y direction) in the light guide plate 3. In FIG.28, a light ray L21 emitted from the lower light source 2-1 is indicatedby a solid line, and a light ray L22 emitted from the upper light source2-2 is indicated by a dotted line. When light enters from such twodirections, light emitted from the light guide plate 3 has peaks in twodirections. Light emitted from the lower light source 2-1 and lightemitted from the upper light source 2-2 are emitted toward a right abovedirection while being maintained parallel to each other throughdisposing the ridgeline 52 of each of the reverse prisms 51 and theextending direction of each of the scattering regions 31 orthogonal toeach other. Therefore, when the ridgeline 52 of each of the reverseprisms 51 and the extending direction of each of the scattering regions31 are not orthogonal to each other, the light ray L21 emitted from thelower light source 2-1 and the light ray L22 emitted from the upperlight source 2-2 are not emitted just above the pattern, and the lightemission state is turned to the state illustrated in FIG. 26 or 27.

[Effects]

As described above, in the display unit according to the embodiment, thescattering regions 31 and the total reflection region 32 are disposed onthe second internal reflection plane 3B of the light guide plate 3, andthe light guide plate 3 allows the first illumination light L1 from thefirst light source 2 and the second illumination light L10 from thesecond light source 7 to selectively exit therefrom; therefore, thelight guide plate 3 equivalently functions as a parallax barrier. Thus,compared to the parallax barrier system stereoscopic display unit inrelated art, the number of components is reduced, and space saving isachievable.

Moreover, in the display unit according to the embodiment, since adensity distribution of the asperities 41 in each of the scatteringregions 31 varies with the distance from the first light source 2,uniformization of the in-plane luminance distribution is achievablethrough improving a luminance distribution in three-dimensional display.Further, since the reverse prism sheet 50 is included as an opticalmember allowing the angular distribution of luminance of light emittedfrom the light guide plate 3 to be varied; therefore, illumination lightwith a desired angular distribution of luminance is obtainable throughreducing variations in angular distribution of luminance of light causedby the asperities 41 provided to the scattering regions 31.

[Verification of Effects by Reverse Prism Sheet 50]

To verify effects by the reverse prism sheet 50, measurement for thefollowing two points was executed. As the reverse prism sheet 50, areverse prism sheet with an apex angle of 65° and a pitch of 18 μm wasused.

(1) Verify whether a light distribution direction of light emitted fromthe light guide plate 3 is turned to the front direction by combinationof the light guide plate 3 with a plurality of asperities 41 formed inthe scattering regions 31 by sandblast processing and the reverse prismsheet 50

(2) Verify whether a light distribution direction of light after passingthrough the reverse prism sheet 50 is turned to the front direction byuse of a light guide plate in which a surface of the second light source7 is subjected to sandblast processing similar to that subjected to thescattering regions 31

FIG. 29 illustrates an angular distribution of luminance in thehorizontal direction (the X direction) of light emitted from the firstlight source 2. FIG. 30 illustrates an angular distribution of luminancein the vertical direction (the Y direction) of light emitted from thefirst light source 2. In FIGS. 29 and 30, an angular distribution ofluminance of light emitted from the first light source 2 after passingthrough the reverse prism sheet 50 and an angular distribution ofluminance of light emitted from the first light source 2 in the casewhere the reverse prism sheet 50 is not provided are illustratedtogether. As illustrated in FIGS. 29 and 30, it was confirmed that lightemitted from the first light source 2 was turned to the front directionafter passing through the reverse prism sheet 50.

FIG. 31 illustrates an angular distribution of luminance in thehorizontal direction (the X direction) of light emitted from the secondlight source 7. FIG. 32 illustrates an example of an angulardistribution of luminance in the vertical direction (the Y direction) oflight emitted from the second light source 7. In FIGS. 31 and 32, anangular distribution of luminance of light emitted from the second lightsource 7 after passing through the reverse prism sheet 50 and an angulardistribution of luminance of light emitted from the second light source7 in the case where the reverse prism sheet 50 is not provided areillustrated together. As illustrated in FIGS. 31 and 32, it wasconfirmed that the angular distribution of luminance of light emittedfrom the second light source 7 were substantially equal to those oflight emitted from the first light source 2, and the light emitted fromthe second light source 7 was turned toward the front direction afterpassing through the reverse prism sheet 50.

2. Second Embodiment

Next, a display unit according to a second embodiment will be describedbelow. It is to be noted that like components are denoted by likenumerals as of the display unit according to the first embodiment andwill not be further described.

FIG. 33 illustrates a configuration example of the display unitaccording to the second embodiment of the present disclosure. Thedisplay unit includes an upward prism sheet 50A as an optical memberinstead of the reverse prism sheet 50 in the display unit in FIG. 1.

The upward prism sheet 50A reduces the above-described variations inangular distribution of luminance of light through shifting lightemitted from the light guide plate 3 toward the front direction as withthe reverse prism sheet 50 in the first embodiment. The upward prismsheet 50A includes a plurality of upward prisms 51A. As illustrated inFIG. 34, each of the upward prisms 51A includes a first oblique plane53A, a second oblique plane 54A, and a ridgeline 52A which is formed atan intersection of the first oblique plane 53A and the second obliqueplane 54A. As illustrated in FIG. 34, a traveling direction of lightemitted from the light guide plate 3 is changed at the first obliqueplane 53A and the second oblique plane 54A of each of the upward prisms51A at least through refraction.

3. Third Embodiment

Next, a display unit according to a third embodiment of the presentdisclosure will be described below. It is to be noted that likecomponents are denoted by like numerals as of the display unitsaccording to the first and second embodiments and will not be furtherdescribed.

FIG. 35 illustrates a configuration example of the display unitaccording to the third embodiment. In the display unit in FIG. 1, thereverse prism sheet 50 and the display section 1 are disposed withspacing; however, in the display unit according to this embodiment, thereverse prism sheet 50 and the display section 1 are bonded together.

An effect in the case where the reverse prism sheet 50 and the displaysection 1 were bonded together in such a manner was verified. In thecase where 3D display was performed, a crosstalk amount in the casewhere the reverse prism sheet 50 and the display section 1 were bondedtogether and a crosstalk amount in the case where the reverse prismsheet 50 and the display section 1 were not bonded together weremeasured. It was confirmed that, compared to the case where the reverseprism sheet 50 and the display section 1 were not bonded together, inthe case where the reverse prism sheet 50 and the display section 1 werebonded together, the crosstalk amount was reduced from 12.6% to 8.8%,because an air interface was reduced through bonding the display section1 and the reverse prism sheet 50 together.

4. Fourth Embodiment

Next, a display unit according to a fourth embodiment of the presentdisclosure will be described below. It is to be noted that likecomponents are denoted by like numerals as of the display unitsaccording to the first to third embodiments and will not be furtherdescribed.

FIG. 36 illustrates a configuration example of the display unitaccording to the fourth embodiment. The display unit is different fromthe display unit in FIG. 1 in that the display unit further includes atransparent or semi-transparent substrate 60 having reflection sections61. The substrate 60 is disposed to face the light guide plate 3 on aside opposite to an emission direction of light from the first lightsource 2 (a side opposite to a side facing the display section 1). Thereflection sections 61 have a role in reflecting back light from thefirst light source 2 into the light guide plate 3 so as not to allow thelight from the first light source 2 to be emitted in a directionopposite to an original emission direction. The reflection sections 61are disposed in positions corresponding to the scattering regions 31.Light use efficiency is improvable through providing the reflectionsections 61.

The reflection sections 61 are configured of, for example, a film ofmetal formed on the substrate 60. As the metal forming the reflectionsections 61, high-reflectivity metal with favorable spectralcharacteristics, such as Al or Ag is preferable. The substrate 60 may bedisposed with spacing from the light guide plate 3 as illustrated in theconfiguration example in FIG. 36, or may be disposed to allow thereflection sections 61 and the scattering regions 31 to be adhered toeach other. Moreover, a metal film may be formed directly on surfaceportions corresponding to the scattering regions 31 of the light guideplate 3, instead of forming the reflection sections 61 on the substrate60. Further, the reflection section 61 may be made of a scattering resinsuch as white ink, instead of the metal film.

Moreover, instead of the substrate 60 having the reflection sections 61,a neutral density filter may be provided.

5. Fifth Embodiment

Next, a display unit according to a fifth embodiment of the presentdisclosure will be described below. It is to be noted that likecomponents are denoted by like numerals as of the display unitsaccording to the first to fourth embodiments and will not be furtherdescribed.

In the first embodiment, an example in which a plurality of very smallasperities are formed on the front surface of the second light source 7by, for example, sandblast processing so as to allow the angulardistribution of luminance of light emitted from the second light source7 to approximate to the angular distribution of luminance of lightemitted from the first light source 2 is described; however, a differentconfiguration may be adopted. FIGS. 37 and 38 illustrate modificationsof the second light source 7.

A second light source 7A illustrated in FIG. 37 is a light guide platesystem surface light source, and includes a light source section 81 anda light guide plate 82. The light guide plate 82 is a prism light guideplate, and includes a prism section 83 on a bottom surface thereof. Theprism section 83 is configured of a mirror plane.

A second light source 7B illustrated in FIG. 38 is a light guide platesystem surface light source, and includes a light source section 91 anda light guide plate 92. The second light source 7B further includes asecond reverse prism sheet 93 on a light emission side thereof. Thesecond light source 7B is a planar light source, and has a uniformin-plane angular distribution of luminance. The second reverse prismsheet 93 allows an angular distribution of luminance of light emittedfrom the second light source 7B to approximate to an angulardistribution of luminance of light emitted from the first light source2.

It is to be noted that, in FIG. 38, the second light source 7B is anedge light system surface light source; however, the second light source7B may be a direct-type surface light source.

6. Other Embodiments

Although the present disclosure is described referring to theabove-described embodiments, the present disclosure is not limitedthereto, and may be variously modified. For example, the display unitsaccording to the above-described embodiments each are applicable tovarious electronic apparatuses having a display function. FIG. 40illustrates an appearance configuration of a television as an example ofsuch an electronic apparatus. The television includes an image displayscreen section 200 including a front panel 210 and a filter glass 220.

Moreover, in the above-described embodiments, a configuration example inwhich the scattering regions 31 and the total reflection region 32 aredisposed on the second internal reflection plane 3B in the light guideplate 3 is described; however, the scattering regions 31 and the totalreflection region 32 may be disposed on the first internal reflectionplane 3A.

Further, in the above-described embodiments, the reverse prism sheet 50and the upward prism sheet 50A are described as examples of the opticalmember allowing the angular distribution of luminance of light to bevaried; however, any other optical member including a plurality ofportions changing a traveling direction of incident light at leastthrough refraction may be used. For example, a lens sheet including aplurality of lenses with refraction as the portions changing thetraveling direction of light may be used.

In the above-described embodiments, a configuration example in which aplurality of scattering regions 31 continuously extending in thevertical direction are arranged side by side in a striped form isdescribed; however, for example, as illustrated in FIG. 39, thescattering regions 31 may have a pattern intermittently extending in thevertical direction.

In the above-described embodiments, as illustrated in FIG. 7 and thelike, light-scattering characteristics are added to the scatteringregions 31 through forming a plurality of asperities 41 on the surfaceof the scattering region 31; however, the surface of the scatteringregion 31 may be coated with a material having light-scatteringcharacteristics such as white ink.

The technology of the present disclosure may have the followingconfigurations.

(1) A display unit including:

a display section displaying an image; and

a light source device emitting light for image display toward thedisplay section, the light source device including one or more firstlight sources, a light guide plate, and an optical member, the firstlight sources emitting first illumination light, the light guide plateincluding a plurality of scattering regions that allow the firstillumination light to be scattered and then to exit from the light guideplate, the optical member being disposed on a light-emission side of thelight guide plate to face the light guide plate and allowing an angulardistribution of luminance of the first illumination light emitted fromthe light guide plate to be varied.

(2) The display unit according to (1), in which

the first illumination light exiting from the light guide plate has anangular distribution of luminance, where luminance in an obliquedirection is higher than luminance in a direction of a normal to asurface of the light guide plate, and

the optical member allows the luminance of the first illumination lightin the direction of the normal to the surface of the light guide plateto be increased.

(3) The display unit according to (1) or (2), in which the opticalmember includes a plurality of portions each allowing a travelingdirection of incident light to be changed at least through refraction.

(4) The display unit according to (3), in which

the portions changing the traveling direction of light are configured ofprisms each having a first oblique plane, a second oblique plane, and aridgeline, the ridgeline being formed at an intersection of the firstoblique plane and the second oblique plane,

each of the plurality of scattering regions is disposed in a fashion toconfigure a pattern continuously extending in a predetermined directionor a pattern intermittently extending in the predetermined direction,and

the ridgeline of each of the prisms and the extending direction of eachof the scattering regions are orthogonal to each other.

(5) The display unit according to any one of (1) to (4), in which

the light guide plate has a plurality of side surfaces,

the one or more first light sources are disposed to face one or more ofthe side surfaces of the light guide plate, and

each of the scattering regions has, on a surface thereof, a plurality ofasperities that provide a light-scattering function, and density of theasperities varies with a distance from the first light source.

(6) The display unit according to (5), in which density of theasperities in each of the scattering regions increases with increasingdistance from the first light source.

(7) The display unit according to any one of (1) to (6), furtherincluding a second light source disposed to face the light guide plate,the second light source applying second illumination light toward thelight guide plate from a direction different from a light-applicationdirection of the first light source,

in which the optical member allows an angular distribution of luminanceof the second illumination light exiting from the light guide plate, aswell as the angular distribution of luminance of the first illuminationlight, to be varied.

(8) The display unit according to (7), in which

the second illumination light has an angular distribution of luminance,where luminance in an oblique direction is higher than luminance in adirection of a normal to a surface of the light guide plate, and

the optical member allows the luminance of the second illumination lightin the direction of the normal to the surface of the light guide plateto be increased.

(9) The display unit according to (7), in which

the display section selectively switches images to be displayed betweenperspective images based on three-dimensional image data and an imagebased on two-dimensional image data, and

the second light source is controlled to be turned off when theperspective images are to be displayed on the display section, and iscontrolled to be turned on when the image based on the two-dimensionalimage data is to be displayed on the display section.

(10) The display unit according to (9), in which the first light sourceis controlled to be turned on when the perspective images are to bedisplayed on the display section, and is controlled to be either turnedoff or turned on when the image based on the two-dimensional image datais to be displayed on the display section.

(11) The display unit according to any one of (1) to (10), furtherincluding a reflection member disposed to face the light guide plate onan opposite side of the light-emission side of the light guide plate,and allowing the first illumination light, that has exited from thelight guide plate onto the opposite side of the light-emission side, toreflect back into the light guide plate.

(12) A light source device including:

one or more first light sources emitting first illumination light;

a light guide plate including a plurality of scattering regions thatallow the first illumination light to be scattered and then to exit fromthe light guide plate; and

an optical member disposed on a light-emission side of the light guideplate to face the light guide plate and allowing an angular distributionof luminance of the first illumination light emitted from the lightguide plate to be varied.

(13) An electronic apparatus provided with a display unit, the displayunit including:

a display section displaying an image; and

a light source device emitting light for image display toward thedisplay section, the light source device including one or more firstlight sources, a light guide plate, and an optical member, the firstlight sources emitting first illumination light, the light guide plateincluding a plurality of scattering regions that allow the firstillumination light to be scattered and then to exit from the light guideplate, the optical member being disposed on a light-emission side of thelight guide plate to face the light guide plate and allowing an angulardistribution of luminance of the first illumination light emitted fromthe light guide plate to be varied.

The present disclosure contains subject matter related to that disclosedin Japanese Priority Patent Application No. 2012-169218 filed in theJapan Patent Office on Jul. 31, 2012, the entire content of which ishereby incorporated by reference.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations, and alterations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalents thereof.

What is claimed is:
 1. A display unit comprising: a display sectiondisplaying an image; and a light source device emitting light for imagedisplay toward the display section, the light source device includingone or more first light sources, a light guide plate, and an opticalmember, the first light sources emitting first illumination light, thelight guide plate including a plurality of scattering regions that allowthe first illumination light to be scattered and then to exit from thelight guide plate, the optical member being disposed on a light-emissionside of the light guide plate to face the light guide plate and allowingan angular distribution of luminance of the first illumination lightemitted from the light guide plate to be varied.
 2. The display unitaccording to claim 1, wherein the first illumination light exiting fromthe light guide plate has an angular distribution of luminance, whereluminance in an oblique direction is higher than luminance in adirection of a normal to a surface of the light guide plate, and theoptical member allows the luminance of the first illumination light inthe direction of the normal to the surface of the light guide plate tobe increased.
 3. The display unit according to claim 1, wherein theoptical member includes a plurality of portions each allowing atraveling direction of incident light to be changed at least throughrefraction.
 4. The display unit according to claim 3, wherein theportions changing the traveling direction of light are configured ofprisms each having a first oblique plane, a second oblique plane, and aridgeline, the ridgeline being formed at an intersection of the firstoblique plane and the second oblique plane, each of the plurality ofscattering regions is disposed in a fashion to configure a patterncontinuously extending in a predetermined direction or a patternintermittently extending in the predetermined direction, and theridgeline of each of the prisms and the extending direction of each ofthe scattering regions are orthogonal to each other.
 5. The display unitaccording to claim 1, wherein the light guide plate has a plurality ofside surfaces, the one or more first light sources are disposed to faceone or more of the side surfaces of the light guide plate, and each ofthe scattering regions has, on a surface thereof, a plurality ofasperities that provide a light-scattering function, and density of theasperities varies with a distance from the first light source.
 6. Thedisplay unit according to claim 5, wherein density of the asperities ineach of the scattering regions increases with increasing distance fromthe first light source.
 7. The display unit according to claim 1,further comprising a second light source disposed to face the lightguide plate, the second light source applying second illumination lighttoward the light guide plate from a direction different from alight-application direction of the first light source, wherein theoptical member allows an angular distribution of luminance of the secondillumination light exiting from the light guide plate, as well as theangular distribution of luminance of the first illumination light, to bevaried.
 8. The display unit according to claim 7, wherein the secondillumination light has an angular distribution of luminance, whereluminance in an oblique direction is higher than luminance in adirection of a normal to a surface of the light guide plate, and theoptical member allows the luminance of the second illumination light inthe direction of the normal to the surface of the light guide plate tobe increased.
 9. The display unit according to claim 7, wherein thedisplay section selectively switches images to be displayed betweenperspective images based on three-dimensional image data and an imagebased on two-dimensional image data, and the second light source iscontrolled to be turned off when the perspective images are to bedisplayed on the display section, and is controlled to be turned on whenthe image based on the two-dimensional image data is to be displayed onthe display section.
 10. The display unit according to claim 9, whereinthe first light source is controlled to be turned on when theperspective images are to be displayed on the display section, and iscontrolled to be either turned off or turned on when the image based onthe two-dimensional image data is to be displayed on the displaysection.
 11. The display unit according to claim 1, further comprising areflection member disposed to face the light guide plate on an oppositeside of the light-emission side of the light guide plate, and allowingthe first illumination light, that has exited from the light guide plateonto the opposite side of the light-emission side, to reflect back intothe light guide plate.
 12. A light source device comprising: one or morefirst light sources emitting first illumination light; a light guideplate including a plurality of scattering regions that allow the firstillumination light to be scattered and then to exit from the light guideplate; and an optical member disposed on a light-emission side of thelight guide plate to face the light guide plate and allowing an angulardistribution of luminance of the first illumination light emitted fromthe light guide plate to be varied.
 13. An electronic apparatus providedwith a display unit, the display unit comprising: a display sectiondisplaying an image; and a light source device emitting light for imagedisplay toward the display section, the light source device includingone or more first light sources, a light guide plate, and an opticalmember, the first light sources emitting first illumination light, thelight guide plate including a plurality of scattering regions that allowthe first illumination light to be scattered and then to exit from thelight guide plate, the optical member being disposed on a light-emissionside of the light guide plate to face the light guide plate and allowingan angular distribution of luminance of the first illumination lightemitted from the light guide plate to be varied.